Extinct species, 107 Extinction of species, 112, 119 F Family of Haeckel, the, 253 Filippo de Filippi, 76 Fish, nature of the, 219 FitzRoy, Captain, 103 _Flora Hallensis_, contribution to the, 37 Fol, 245 _For Darwin_, 230 _Force and Matter_, 201 Forms, science of, 190-2 Form-unities, 207 _Free Science and Free Teaching_, 285 Freedom of research, 75, 156 French rule in Prussia, 25 Freytag, Gustav, 21, 29 Friedenthal, 310 Frog, the, 219 〃 , evolution of the, 222 G Galapagos Islands, Darwin in the, 116 Galileo, 16 Gandtner, 37 Gastræa, the, 276 Gastræa-theory, the, 278 Gastrula, the, 277 Gegenbaur, Karl, 62-4 Genealogical tree of organisms, 149, 152, 226 _Generelle Morphologie_, the, 188 Genius, 102 Geology, 108 〃 and evolution, 167 _Geryonidæ_, the, 177 Gill-slits in the human embryo, 269 Giltsch, Adolph, 289 Glyptodon, the, 113 Gneisenau, 29 God, Haeckel’s conception of, 133-5, 236 〃 , the new conception of, 19 Goethe, 17 〃 , evolution in works of, 238 〃 on morphology, 190-1 Goethe’s influence on Haeckel, 41-6 Gramzow, Otto, on Haeckel, 295 Greece, visit to, 257 Greeff, Richard, 244 Greek, Haeckel’s knowledge of, 36 _Green Henry_, 45 Gryptotherium, the, 113 Gude, Karl, 37 H Haeckel abandons theology, 75, 133 〃 , æsthetic element in, 83, 185 〃 , ancestry of, 21 Haeckel and Darwin, 127, 241 〃 〃 Gegenbaur, 62 〃 〃 Müller, 69 〃 〃 Virchow, 163, 284 〃 as a physician, 80 〃 〃 traveller, 256 〃 at Down, 241 〃 at Stettin, 146 〃 , birth of, 29 〃 , boyhood of, 31-3 〃 , early education of, 34-50 〃 embraces evolution, 137 〃 , family of, 253 〃 , first marriage of, 100 〃 goes to Jena, 100 〃 , honours awarded to, 10, 298, 300 〃 in Heligoland, 69 〃 in Italy, 82 〃 in the Canaries, 240 〃 , medical training of, 76 〃 , parents of, 28 〃 , personal charm of, 146 〃 , political views of, 301 〃 , recent popularity of, 295 〃 reconstructs zoology, 181 〃 , religion of, 230 〃 , second marriage of, 253 〃 , university training of, 54 Haeckel, Councillor Karl, 29, 32 〃 , Walter, 83 _Haeckel’s Critics Answered_, 307 Heine, 21 Heligoland, the first journey to, 69 Heliosphæra, the, 141 Heliozoa, the, 258 Heredity, a theory of, 284 Hertwig, Oscar, 257 Hertwig, R., 189 Histology, 56 _History of Creation_, the, 262 History, unity of, 44 Holy Land, travels in the, 259 Horton, Dr., on Haeckel, 312 Hüffer, Hermann, 21 Humboldt, 46, 144 〃 foundation, the, 31 Huschke, Agnes, 253 Huxley on the origin of man, 180 I Illustrations, charges against Haeckel’s, 267-8 Imagination in science, 200 Independence, Haeckel’s early sense of, 31 _Indische Reisebriefe_, the, 261 Individuality, nature of, 207, 211 〃 , stages of, 209 Infusoria, the, 78 International Congress of Freethinkers, the, 316 _Irene_, 176 Ischia, journey to, 87 Italy, appreciation of Haeckel in, 299